Chlorine-enhanced donor-acceptor hydrophenazine COF for accelerated Li+ kinetics in lithium-ion capacitor anodes

Covalent organic frameworks (COFs), with customizable/functionalized skeleton and tunable/ordered channel structure, demonstrate high capability for rapid Li + intercalation/deintercalation to address the challenge of dynamic charge storage imbalance between battery-type anodes and capacitor-type cathodes in lithium-ion capacitors (LICs). Herein, we firstly synthesized hydrophenazine (HP)-linked COF HA-DQ powders with a pore size of 2.2 nm, featuring a fully conjugated crystalline D-A skeleton with enhanced local polarization. Further, the –Cl group with strong electronegativity was introduced into form COF HA-Cl to employ its synergistic interaction with active N sites for further inducing pronounced local polarization, which facilitates rapid Li + intercalation/deintercalation for ensuring accelerated anodic kinetics (simulated Li + diffusion energy barrier value of 0.018 eV in COF HA-Cl ). Then, following the COF HA-Cl anode prelithiated to 800 mAh g −1 , the constructed AC//COF HA-Cl LICs deliver the optimal capacity performance, such as a high energy density of 24.4 Wh kg −1 at a power density of 100 W kg −1 , and exhibited strong good cycling stability, maintaining 82.6 % of its initial capacity after 2000 cycles. This work addressed kinetic and capacity imbalance in LIC electrodes through molecular and pore structure design of COF materials, paving the way for future miniaturized and wearable electronics.